- G(-) rod; species encountered in clinical practice include P. mirabilis, P. vulgaris, P. penneri
- Typically come up as susceptible to nearly all antibiotics EXCEPT tetracycline and nitrofurantoin (fluoroquinolone and Bactrim resistance is also on the rise), BUT a portion of strains produce AmpC, a beta-lactamase which the organism can increase production of during therapy when exposed to certain beta lactams. These organisms may show resistance to ampicillin and 1st generation cephalosporins.
- Use cefepime, a carbapenem, or a non beta-lactam even if cultures show sensitivity to other beta-lactams (and especially if patient has received doses of other beta lactams during their stay), otherwise may lead to resistance development during therapy and treatment failure.
- Once sensitivities are available, de-escalation to a non-beta-lactam is possible if sensitive
- Common GI colonizer as part of normal flora
- P. vulgaris and P. penneri (generally more resistant) more commonly associated with healthcare setting
- Not a common cause of pneumonia or bacteremia, more likely to be involved in UTI